1. Field of the Invention
The invention relates generally to an instrument panel assembly. More specifically, the invention relates to a light emitter and a light receiver that cooperate to detect a desired instrument setting change.
2. Related Technology
An instrument panel for the passenger compartment of a motor vehicle passenger compartment or in an aircraft cockpit typically has a plurality of instrument display components that display various vehicle settings and conditions, such as speed, mileage, and fuel level. During the operation of the vehicle, the vehicle occupant may desire to change an instrument setting, such as to reset a trip odometer or to switch the units of measurement of the display component. Direct access to a display component, however, is difficult because the instrument panel typically includes a base panel supporting the instrument display component(s) and a transparent protective cover spaced apart from the base panel to protect the instrument display components from accidental contact and to prevent dirt and dust from collecting thereon.
To make these components accessible to the vehicle operator, a mechanically-actuated instrument control member typically extends from the base panel, across a gap distance, and through an opening in the protective cover. A typical control member is an elongated, generally cylindrical, rod or knob that is able to be rotated and/or depressed by the vehicle operator to change a vehicle display setting. One common mode of operation is for this type of knob to be rotated to change an odometer display between a “trip odometer mode” and a “vehicle odometer mode” and to be depressed to reset the trip odometer.
This type and other types of mechanically-actuated instrument control members typically must extend across the gap distance between the respective panels, which may be aesthetically undesirable. Furthermore, the opening in the protective panel for the knob may allow dirt or other debris to gain access to and collect on the surface instrument display components.
Another type of instrument control assembly utilizes an optoelectronic keypad to detect desired instrument setting changes. More specifically, as disclosed in U.S. Application Publication No. 2003/0090470, published on May 15, 2003, an optoelectronic keyboard is spaced apart from a light emitter and a light receiver, which are adjacent to each other. The light emitter emits light towards a keyboard surface in a direction that is perpendicular thereto when the keyboard is in its natural resting position. Therefore, the light is reflected back to the light emitter (as opposed to being reflected to the light receiver) when the keyboard is in its natural resting position. However, when a user depresses a portion of the keyboard during operation of the control assembly, the keyboard surface is deflected and the light emanating from the light emitter is reflected in multiple, random directions. The light receiver is positioned along on the path of one or more of the deflected directions so as to receive the light and complete an electrical connection between the light emitter and the light sensor. This type of control assembly, however, may fail to complete the electrical connection due to unpredictable or inconsistent light deflection based on slight variations in the position of the user's finger when depressing the keyboard and based on slight variations in the depressing force used. Furthermore, multiple light receivers to receive the unpredictable light may increase the complexity and/or increase the component cost of the assembly.
It is therefore desirous to provide an instrument control assembly that consistently and accurately detects a desired instrument setting change while having a relatively simple, low cost design and an aesthetically pleasing design.